Papers by 111 Rohit Mahesh Khedkar
Energy has been rated as the single most important issue facing humanity in the current as well a... more Energy has been rated as the single most important issue facing humanity in the current as well as next 50 years. Securing clean energy has become the top priority of most developed countries. Considering the rapid increase in energy demand worldwide, intensifying the heat transfer process and reducing energy loss due to ineffective use have become an increasingly important task. Fundamentally, energy conversion and transportation occur at atomic or molecular levels, Nanoscience and nanotechnology are expected to play a significant role in revitalizing the traditional energy industries and stimulating the emerging renewable energy industries. Nanofluid is a modern engineering heat transfer fluid with superior potential for enhancing the heat transfer performance of conventional fluids such as water, ethylene glycol and oils. It is consisting of solid nanoparticles with sizes typically of 1-100 nm suspended in base fluids. Many attempts have been made to investigate its important thermal properties, i.e. thermal conductivity; however, no definitive agreements and idea have emerged about this property. This article reports the effect of different nanomaterial on the thermal conductivity enhancement of nanofluids experimentally. TiO 2 , Fe 3 O 4 and Al 2 O 3 nanoparticles dispersed in water and ethylene glycol with volume concentration of 1-7.5 vol. % is used in the present study. A transient hot-wire apparatus (KD2 pro) is used for measuring the thermal conductivity of nanofluids. The results show that all the heat transfer fluids show an increase in thermal conductivity with the addition of nanoparticles in it. The measured thermal conductivity of nanofluids increased as the particle concentrations increased and are higher than the values of the base liquids. This confirms the effect of volume concentration of nanoparticles on the thermal conductivity enhancement.
International Communications in Heat and Mass Transfer, 2014
ABSTRACT In the present study, the heat-transfer characteristics of TiO2–water nanofluids as a co... more ABSTRACT In the present study, the heat-transfer characteristics of TiO2–water nanofluids as a coolant in concentric tube heat exchanger are presented. The heat exchanger is fabricated from copper concentric inner tube with length 1000 mm. The nanofluids are the mixture of water as base fluid and TiO2 particles in nano-range. The results obtained from the nanofluids cooling in concentric tube heat exchanger are compared with those from base fluids as coolant. Effects of inlet flow rate of hot fluids, Reynold's number and composition of nanofluids on concentric tube heat exchanger are considered. It is observed that the average heat transfer rates for nanofluids as a cooling media are higher than those for the water which is also used as cooling media, and this increases with concentration of nanofluid composition. The results of this study have technological importance for the efficient design of concentric tube heat exchanger to enhance cooling performance at low heat flux cooling systems.
Procedia Engineering, 2013
Concentric tube heat exchanger is a low cost, which increases reliability by restricting mixing o... more Concentric tube heat exchanger is a low cost, which increases reliability by restricting mixing of fluids exchanging heat. Concentric tube heat exchanger has potential application such as heat recovery from engine cooling circuit, oil cooling, desuperheating in refrigeration and air conditioning, dairy, and chemical industry, pharmaceutical industry, refinery, etc. This paper concentrate on an experimental study on concentric tube heat exchanger for water to nanofluids heat transfer with various concentrations of nanoparticles in to base fluids and application of nanofluids as working fluid. The experimental results on this type of heat exchanger configuration and water nanofluids could not be located in literature. Overall heat transfer coefficient was experimentally determined for a fixed heat transfer surface area with different volume fraction of nanoparticles in to base fluids and results were compared with pure water. It observed that, 3 % nanofluids shown optimum performance with overall heat transfer coefficient 16% higher than water.
Journal of Nano Research, 2013
In the present research work, an anatase structure titanium dioxide nanoparticle was synthesized ... more In the present research work, an anatase structure titanium dioxide nanoparticle was synthesized by hydrolysis of titanium isopropoxide in the presence and absence of ultrasonication. The resultant product suspension was peptized for getting narrow size distribution. The synthesized nanoparticles are used for preparation of nanofluids with different volume percent loading of nanoparticles in water ranging from 1% to 5%. The characterization of particles was carried out by TEM, XRD. Our result shows that the use of ultrasonic technique has a significant effect on the homogeneity and then size of TiO2nanoparticles. Viscosity of nanofluids was demonstrated with rheometer (TA instruments). Viscosity results confirmed Newtonian behavior of nanofluids and showing increasing trends with addition of nanoparticles in base fluids. The dispersion of nanoparticles in nanofluids is studied with unique method of UV visible spectrophotometer, which confirm good dispersion stability prepared nanofl...
Journal of Experimental Nanoscience, 2013
ABSTRACT This paper presents experimental and theoretical determination of the effective thermal ... more ABSTRACT This paper presents experimental and theoretical determination of the effective thermal conductivity of various base fluids and nano TiO2 composition. Ultrasonically assisted sol–gel method was used for synthesising anatase TiO2 nanoparticles and dispersing them into base fluids using sonication for the synthesis of nanofluids. It is observed that thermal conductivity enhancement is significantly higher than that of base fluid. The thermal conductivity shows an increment with the addition of nanoparticles and confirms a 22% enhancement achievable in base fluids. The effect of base fluids is a complex idea and difficult to understand; lower base fluid viscosities were supposed to contribute higher in enhancement of thermal conductivity, but another important factor; i.e. fluid nanoparticles surface interaction, nanoparticles crystal type also contributes in enhancement. In the further study, as the sonication time increases; an improvement in the thermal conductivity of nanofluids is also observed. Except water-based nanofluids, all others show reasonably good agreement with the data predicted by Bruggeman model and the prediction is in the range of 5%. This study is important since it covers base fluids with a wide range of thermal conductivity and viscosity.
International Communications in Heat and Mass Transfer, 2013
In the present study, the heat transfer characteristics of Al 2 O 3water nanofluids as a coolant ... more In the present study, the heat transfer characteristics of Al 2 O 3water nanofluids as a coolant used in concentric tube heat exchanger are presented. The heat exchanger is fabricated from copper concentric inner tube with a length of 1000 mm. The nanofluids are the mixture of water as base fluid and Al 2 O 3 particles in nanorange. The results obtained from the nanofluids cooling in concentric tube heat exchanger are compared with those from base fluids. The effects of inlet flow rate of hot fluids, Reynold's number and composition of nanofluids on concentric tube heat exchanger are considered. It is observed that average heat transfer rates for nanofluids as cooling media are higher than those for the water as cooling media, and this increases with concentration of nanofluids' composition. The results of this study have technological importance for the efficient design of concentric tube heat exchanger to enhance cooling performance at low heat flux cooling systems.
International Communications in Heat and Mass Transfer, 2012
In this paper the effect of CuO nanoparticles on the thermal conductivity of base fluids like mon... more In this paper the effect of CuO nanoparticles on the thermal conductivity of base fluids like mono ethylene glycol and water was studied. Both the base fluids showed enhancement in effective thermal conductivity. This enhancement was investigated with regard to various factors; concentration of nanoparticles, types of base fluids, sonication time and settlement time. For both the base fluids, an improvement in thermal conductivity was found as concentration of nanoparticles increased due to interaction between particles. It was also found that as the sonication time was increased, there was furthermore an improvement in the thermal conductivity of the base fluids. Effect of base fluids is the complex idea to understand. Lower base fluid's viscosities are supposed to contribute grater enchantment, but another factor of fluid nanoparticles surface interaction also more important. The experimentally measured thermal conductivities of base fluid's nanoparticles suspension were compared to a variety of models (Maxwell, Hamilton-Crosser and Bruggeman Model). It is observed that none of the mentioned models were found to predict accurately the thermal conductivities of nanofluids.
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Papers by 111 Rohit Mahesh Khedkar